In the course of manufacturing a semiconductor device, for example, a film forming process such as an oxidizing process, a nitriding process or the like, an etching process, and the like are performed with respect to a workpiece such as a semiconductor wafer or the like through the use of plasma. Recently, there is an increasing demand for coping with miniaturization in an effort to develop a device for the next and subsequent generation. In the meantime, from the viewpoint of enhancing production efficiency, the size of a workpiece is growing larger.
As the related art regarding a plasma process, there has been proposed to provide a mode generation preventing part, which scatters or absorbs a surface wave in order to suppress mode jump of surface-wave-excited plasma.
Furthermore, there has been proposed a plasma processing apparatus in which microwave introduction mechanisms for introducing microwaves into a process container are provided at a plurality of locations. This apparatus is configured to avoid fixation of the positions of antinodes and nodes of a standing wave in the process container. For that purpose, the phases of the microwaves inputted to the microwave introduction mechanisms are adjusted so that, in the adjacent microwave introduction mechanisms, the microwave input phase of one introduction mechanism is fixed and the microwave input phase of the other introduction mechanism is changed according to a periodic waveform.
In a plasma processing apparatus that introduces a plurality of microwaves, in order to cope with the enlargement of a workpiece without unnecessarily increasing the number of microwave introduction regions, it is effective to use a large-sized microwave transmitting member and to share the microwave transmitting member with a plurality of microwaves. However, in the case of increasing the size of the microwave transmitting member, mode jump of plasma is likely to occur. This is because only the microwave having an integral multiple of a half wavelength exists in the interior of the microwave transmitting member so that the electron density of plasma generated by the corresponding microwave becomes a discontinuous value. When the mode jump of plasma occurs, the electron density of plasma is greatly changed. This adversely affects the homogenization of the processing on the workpiece.